This invention relates to surveillance of telephone calls over a public communications link and is particularly concerned with providing assistance for such surveillance to law enforcement agencies. It particularly concerns surveillance of voice over IP (i.e., VOIP) (e.g., cable) networks.
Requirements for enabling surveillance of electronic communications have been enacted into public law (e.g., Public Law 103-414 enacted Oct. 25, 1994 CALEA Communications Assistance for Law Enforcement Act) reciting requirements for assuring law enforcement access to electronic communications. Such access is required to be in real time, have full time monitoring capabilities, simultaneous intercepts, and feature service descriptions. The requirements specifically include capacity requirements and function capability. It is incumbent upon communication carriers to provide such capability and capacity.
While initially limited in scope, at present, to certain communications technology it is almost assured that it will be extended to new forms of communication. New technologies require extension of CALEA to the new phone system technologies.
In IP telephony the location of a called party may be dynamic and in motion. It may be desirable to monitor a called party IP telephone even as the location of that phone changes. It may also be appropriate to allow a calling party to remain unaware of the new DN.
Monitored calls are intercepted and rerouted to a changed location/directory number of a called party while appearing to the caller to be at the same directory number, in accord with the principles of the invention, by intervention of an IP Address Mapping check Point (IP-AMCP) which duplicates the voice to a monitoring location, automatically identifies the types of networks to be traversed to the new location and adapts the duplicated voice message to traverse such network types. Surveillance is enabled to be conducted at more than one monitoring location each of which many are widely separated from the other.
In a particular illustrative embodiment an authorized surveillance agent transmits a valid request to an IP Address Mapping Check Point (IP-AMCP) which in response intercepts voice packets to and from the targeted IP phone. The duplicated voice packets are transmitted to the designated monitoring location. The IP-AMCP determines the type of voice signal to be transmitted to the terminal monitoring station. If the monitoring location is serviced by an IP telephony network the monitored traffic is duplicated by the IP-AMCP in IP format to an IP Directory Number (DN) as programmed in accord with an IP Phone Intercept List (IP-PIL). If the monitoring location is serviced by a PSTN network a PSTN Check Point (PSTN-CP) establishes a trunk connection with the Local Digital Switch (LDS) and receives incoming voice packets at the IP-AMCP which the PSTN-CP converts to Time Division Multiplex (TDM) voice and uses a trunk (i.e., T1) to communicate with the LDS.
A further arrangement allows a caller to call an original number of a changed DN being monitored with surveillance transferred to a new DN of the called party (i.e., the victim) at a new physical location. In this mode the IP-AMCP intercepts the call and queries the IP-PIL for new delivery instructions such as the new destination PSTN or IP phone number.
If the new call transferred to the IP DN needs to be protected, the surveillance agent can remotely turn on an xe2x80x9caddress maskingxe2x80x9d feature on the IP-AMCP. Once the feature is activated, the called party""s new DN (i.e., calling ID) is replaced with the original DN therefore the call being made appear as the same destination location to the caller.
If the call is initiated from an IP network to a subscriber transferred from IP telephone service back to PSTN network service or vice versa, the IP-PIL query result is used by the IP-AMCP to notify the PSTN-CP to make a new a connection to the Local Digital Switch (LDS)
If the call is initiated from an IP network to an IP phone user at a new IP location, the IP-PIL query result is used by the IP-AMCP to route the call to the new IP location.
If the call is initiated from the PSTN to an old IP phone user at a new PSTN location the IP-AMCP first intercepts the call, queries the IP-PIL and notifies the originating LDS to establish connection with the new destination LDS directly.